Method and apparatus for performing inter-frequency and/or inter-radio access technology measurements

Abstract

Techniques for performing inter-frequency and/or inter-radio access technology (RAT) measurements are disclosed. A multi-receiver wireless transmit/receive unit (WTRU) may receive downlink transmissions via a plurality of downlink carriers simultaneously. The WTRU may perform inter-frequency and/or inter-RAT measurements using an inactive receiver without measurement gaps if at least one receiver is inactive. If the WTRU receives a measurement order on a disabled carrier, the WTRU may perform measurements on the disabled carrier without measurement gaps using an inactive receiver while maintaining a status of the disabled carrier as disabled. The WTRU may perform the measurements autonomously if a trigger condition is met and at least one receiver is inactive. If all receivers are active, the WTRU may perform the measurements using measurement gaps, that may be configured on a downlink carrier, or alternatively, on an unpaired downlink carrier, or alternatively, on a subset of associated downlink uplink carrier pairs.

The invention claimed is: 
     
       1. A method implemented in a multi-receiver wireless transmit/receive unit (WTRU) for performing inter-frequency and/or inter-radio access technology (RAT) measurements, the method comprising:
 determining whether to use either an inactive receiver or measurement gaps for inter-frequency and/or inter-RAT measurements based on an activation status of carriers at a physical layer; and 
 performing inter-frequency and/or inter-RAT measurements using either an inactive receiver or measurement gaps based on the determination. 
 
     
     
       2. The method of  claim 1  wherein the inter-frequency and/or inter-RAT measurements are performed using an inactive receiver without configuring measurement gaps on a condition that at least one inactive receiver is available. 
     
     
       3. The method of  claim 2  wherein the inter-frequency and/or inter-RAT measurements are scheduled autonomously by the WTRU. 
     
     
       4. The method of  claim 1  further comprising:
 receiving a measurement order on a disabled carrier, wherein the inter-frequency and/or inter-RAT measurements are performed using an inactive receiver on the disabled carrier without measurement gaps while maintaining a status of the disabled carrier as disabled at the physical layer. 
 
     
     
       5. The method of  claim 1  wherein the inter-frequency and/or inter-RAT measurements are performed using measurement gaps on a condition that there is no inactive receiver available. 
     
     
       6. The method of  claim 5  wherein the measurement gaps are configured on a downlink carrier and not on an uplink carrier. 
     
     
       7. The method of  claim 5  wherein the measurement gaps are configured on an unpaired downlink carrier and not on a paired downlink carrier. 
     
     
       8. The method of  claim 5  wherein the measurement gaps are configured on a subset of associated downlink-uplink carrier pairs. 
     
     
       9. The method of  claim 1  further comprising:
 determining whether a trigger condition for the inter-frequency and/or inter-RAT measurements is met, wherein the inter-frequency and/or inter-RAT measurements are performed on a condition that the trigger condition is met. 
 
     
     
       10. The method of  claim 1  further comprising:
 detecting a home Node-B (HNB) cell or a home evolved HNB (eHNB) cell; 
 sending a proximity indication on a condition that an identity of the detected HNB or eHNB cell is in a list that the WTRU received from a network; and 
 performing the inter-frequency and/or inter-RAT measurements on a frequency carrier or an RAT of the detected HNB or eHNB cell. 
 
     
     
       11. A multi-receiver wireless transmit/receive unit (WTRU) for performing inter-frequency and/or inter-radio access technology (RAT) measurements, the WTRU comprising:
 a receiver configured to receive via at least two downlink carriers simultaneously; and 
 a processor configured to determine whether to use either an inactive receiver or measurement gaps for inter-frequency and/or inter-RAT measurements based on an activation status of carriers at a physical layer, and perform inter-frequency and/or inter-RAT measurements using either an inactive receiver or measurement gaps based on the determination. 
 
     
     
       12. The WTRU of  claim 11  wherein the processor is configured to perform the inter-frequency and/or inter-RAT measurements using an inactive receiver without configuring measurement gaps on a condition that at least one inactive receiver is available. 
     
     
       13. The WTRU of  claim 12  wherein the processor is configured to schedule the inter-frequency and/or inter-RAT measurements autonomously. 
     
     
       14. The WTRU of  claim 11  wherein the processor is configured to receive a measurement order on a disabled carrier, and perform the inter-frequency and/or inter-RAT measurements using an inactive receiver on the disabled carrier without measurement gaps while maintaining a status of the disabled carrier as disabled at the physical layer. 
     
     
       15. The WTRU of  claim 11  wherein the processor is configured to perform the inter-frequency and/or inter-RAT measurements using measurement gaps on a condition that there is no inactive receiver available. 
     
     
       16. The WTRU of  claim 15  wherein the measurement gaps are configured on a downlink carrier and not on an uplink carrier. 
     
     
       17. The WTRU of  claim 15  wherein the measurement gaps are configured on an unpaired downlink carrier and not on a paired downlink carrier. 
     
     
       18. The WTRU of  claim 15  wherein the measurement gaps are configured on a subset of associated downlink uplink carrier pairs. 
     
     
       19. The WTRU of  claim 11  wherein the processor is configured to determine whether a trigger condition for the inter-frequency and/or inter-RAT measurements is met, and perform the inter-frequency and/or inter-RAT measurements on a condition that the trigger condition is met. 
     
     
       20. The WTRU of  claim 11  wherein the processor is configured to detect a home Node-B (HNB) cell or a home evolved HNB (eHNB) cell, send a proximity indication on a condition that an identity of the detected HNB or eHNB cell is in a list that the WTRU received from a network, and perform the inter-frequency and/or inter-RAT measurements on a frequency carrier or an RAT of the detected HNB or eHNB cell.